What counts as a stimulus?

Classroom resources

Load these into Waypoints Prepare: choose Load URL and paste the copied address, or download the file and import it. In Prepare, the worksheet's Teacher edition shows the answers; the student copy hides them.

• Slides Download Copy address for Prepare Present from the browser, or export to PowerPoint or PDF.
• Worksheet Download Copy address for Prepare Print the student copy; the Teacher edition has the answers.

Students will be able to

• I can explain that a stimulus is a change inside or outside the body.
• I can name the parts of the stimulus–response pathway and what each does.
• I can trace an internal and an external stimulus through the pathway.

Timing

Engage and Explore 7 min · Explain 8 min · Evaluate 3 min · Typical adds 2 min, Wider about 2 min

Before class

A concept tutorial for introducing or revising the idea; it does not replace a reaction-time practical (the ruler drop) or the knee-jerk reflex. Set the width with ?width=minimum, typical (default) or wider.

The hinge misconception is that stimuli are only external. Three of the five board stimuli are internal on purpose.

Board notes: each pathway is simplified to one receptor, one command centre and one effector; the blood sugar and water pathways mix glands and hormones into the boxes, which the next lessons separate.

Running the lesson

1. Engage: count how many chose 'only things outside you'.
2. Explore: ask which stimuli they would never notice happening.
3. Explain: the sort is the checkpoint; 'cold wind' prompts the external change / internal effect distinction.

The hard part (on purpose)

Placing each part on the pathway, especially changes inside the body. When a student skips one, ask what detects the change and what carries out the response.

When students get stuck

Answers to the checks

1. Engage: what is a stimulus?: Which of these is a stimulus?
   Any change your body detects, outside or inside: blood sugar rising and body water falling are stimuli too, though you don't notice them.
2. Explore: follow the signal: Follow at least four stimuli through the pathway, including two internal ones.
   
3. Inside or outside: Internal or external stimulus?
   A loud bang → External; Blood sugar rising → Internal; The smell of toast → External; Body temperature falling → Internal; Too little water in the blood → Internal; Cold wind on your skin → External
4. The parts: Match each part of the pathway to what it does.
   Stimulus → D. A change inside or outside the body; Receptor → B. Detects the change; Command centre → C. Processes the information and decides; Effector → E. A muscle or gland that carries out the response; Response → A. What the body does
5. Hot pan: In the hot pan pathway, which is the effector?
   The arm muscles
6. Smell receptors: The smell of toast is the stimulus. Which is the receptor, and what does it do?
   Smell receptors in the nose: they detect chemicals from the toast and send impulses to the brain
7. Elaborate: a new pathway: A runner's muscles use oxygen fast, so carbon dioxide in the blood rises. Breathing speeds up. Sort each into its part of the pathway.
   Carbon dioxide in the blood rises → Stimulus; Chemical receptors in blood vessels and the brain → Receptor; Brain stem → Command centre; Diaphragm and rib muscles → Effector; Faster, deeper breathing → Response
8. Elaborate: plants respond too: A seedling on a windowsill bends towards the light. Which part of the pathway is missing compared with your body?
   There are no nerves: the command is a plant hormone (auxin) carried in the plant, not an impulse
   Plants still detect a stimulus and respond, but they coordinate with hormones only.

Stretch and support

Stretch: In the water pathway, the response makes the stimulus go away. Find another pathway on the board where that happens.

Support: Give a five-box strip to fill in for each stimulus clicked.

Coach prompt (optional)

For a student who has done the lesson and is still stuck. They paste it into an AI tool your school allows; it asks questions about this lesson's one idea and doesn't give answers. Students see it on the course recap page only through a link ending in ?coach=1: recap with coach prompts.

You are a patient science coach for a Year 9 student in Australia. Help me understand ONE idea only, from the lesson "What counts as a stimulus?".

The idea: Stimuli and receptors — detecting change: I can distinguish internal from external stimuli and identify the receptor type involved in detecting a named stimulus.

What understanding looks like:
- Distinguishes internal from external stimuli with examples
- Identifies an appropriate receptor for a named stimulus and describes its role

Mistakes students often make here:
- A student says blood sugar isn't a stimulus because you can't feel it.
- A student calls the skin the effector.

How to coach me (rules from the Waypoints Kit coach):
- Ask me one short question at a time (2 to 4 sentences) and wait for my answer. Never give me the answer before you have heard my thinking, and don't hide the answer inside your question.
- Start in Discover: ask me to explain the idea in my own words, or to predict what happens in a simple example. I can switch any time: "teach it back" (you play a beginner and I explain), "spot the flaw" (you show me an answer with one common mistake and I find it), or "check" (I explain, and you tell me what is solid and what to revisit).
- If I am stuck or say "just tell me", ask what I think first, then give a small hint or a simpler example. Explain only after I have had a real go.
- Stay in this idea: don't teach later ideas or add extra content. If I ask about something else, say it is for another lesson and bring me back.
- After you help, ask me one reflective question, such as how I know my answer is right or what I would check.
- Praise my effort and method, not my ability.
- You can be wrong: if I rely on something you said, remind me to check it against my notes or the lesson. If you don't know, say so.
- Use simple words.
- Stop when I can explain the idea in my own words and get one new example right. Then tell me to go back to the lesson "What counts as a stimulus?".

Exit ticket

Give one internal stimulus and name its receptor and effector.

For example: body temperature rising; temperature receptors in the brain; sweat glands.

What each step is for

• Engage: what is a stimulus?: Students who think stimuli are only things outside the body (light, sound, touch) will pick the narrow answer; the board includes changes inside.
• Explore: follow the signal: Watching five different stimuli travel through the same five boxes makes the pathway a pattern, not a list to memorise.
• Explain: the pathway: Naming the part each step plays, and sorting internal from external, are the two pieces of the hinge.
• Elaborate: a new pathway: Applying the pathway to an unseen example shows the pattern has transferred.
• Elaborate: plants respond too: Plants detect and respond to stimuli without nerves, which separates the pathway idea from the nervous system.

Where it leads

Next: building pathways yourself and why the command centre matters (node 2), then nerves versus hormones (node 4) and feedback (node 5).

In class: ruler-drop reaction times; knee-jerk reflex; pupil response with a torch.